Best tools for Backend API Design

Cloud-native distributed vector search engine built for Kubernetes with automatic indexing and horizontal scaling.

Vald is a highly scalable distributed approximate nearest neighbor (ANN) vector search engine designed for cloud-native, Kubernetes-based architectures. Maintained by LY Corporation and listed in the CNCF Landscape, it uses the NGT algorithm (developed at Yahoo Japan), supports automatic incremental index backup, and handles billion-scale datasets across loosely coupled microservice components that scale horizontally via Helm.

Library for efficient similarity search and clustering of dense vectors at billion-scale.

FAISS is Meta AI Research's open-source library for efficient similarity search and clustering of dense vectors. It implements approximate nearest-neighbor algorithms designed to scale to billions of vectors, with optimized indexes that fit in RAM and GPU acceleration for the largest workloads. Engineering teams use FAISS as the retrieval primitive underneath custom RAG pipelines, recommendation systems, and large-scale embedding search infrastructure.

Header-only C++ implementation of HNSW for fast approximate nearest-neighbor search.

hnswlib is a header-only C++ library implementing the Hierarchical Navigable Small World (HNSW) graph algorithm for approximate nearest-neighbor search, with Python bindings and a tiny dependency footprint. Originally developed by the nmslib team, it has become the default HNSW implementation embedded inside many vector databases and search products. Engineers use it directly when they want HNSW retrieval without pulling in a heavyweight vector DB.

Embedding-first search and discovery engine for AI-powered product experiences.

Marqo is an open-source tensor search engine that combines embedding generation and vector search in a single API, removing the need to manage separate embedding pipelines and vector databases. Built for product discovery and multi-modal search, it lets teams index text, images, and structured data together, returning ranked results based on semantic similarity rather than keyword overlap.

Sandboxes for coding agents — Linux VMs, Git, and deploys in one box

Freestyle is YC-backed sandbox infrastructure built for AI coding agents, shipping secure Linux VMs with nested virtualization, Git servers, and one-click web deploys. It lets agents run real workloads, branch repos, and deploy apps under short-lived identities while billing only for active compute. Used in production by vly.ai, Rork, and Vibeflow.

High-recall Postgres vector search at billion scale

VectorChord is a Postgres extension from TensorChord that brings high-recall vector search to PostgreSQL. As the spiritual successor to pgvecto.rs, it combines IVF indexes with RaBitQ quantization to deliver Pinecone-class performance at billion-vector scale while keeping all data inside a single Postgres database — no separate vector store, no two-system sync, no rewrites when the workload grows.

AI-native database for hybrid RAG retrieval

Infinity is an AI-native database from InfiniFlow that unifies dense vectors, sparse vectors, tensors, and full-text search in a single engine. Built for retrieval-augmented generation (RAG) at scale, it powers hybrid search workflows where lexical matching, semantic similarity, and reranking all happen against one storage layer instead of four loosely coupled services.

ByteDance high-performance JSON library

Sonic is ByteDance's blazingly fast JSON serialization library accelerated by JIT compilation and SIMD instructions. It achieves 3x faster throughput than Go's standard library while using 75% less memory and 99% fewer allocations. Drop-in compatible with encoding/json, it handles both simple Marshal/Unmarshal operations and streaming APIs for high-throughput services processing millions of events.

Open-source multi-protocol API client

Firecamp is an open-source API DevTool supporting REST, GraphQL, WebSocket, and Socket.IO protocols as a lightweight alternative to Postman. It provides IntelliSense, team collaboration with shared workspaces, and seamless import from OpenAPI, Insomnia, AsyncAPI, and HAR formats. Each protocol gets a dedicated testing playground with response metrics including time, size, and status codes.

Real-time analytics OLAP database

ClickHouse is an open-source column-oriented database built for real-time analytical queries on massive datasets. Its columnar storage with advanced compression and vectorized query execution using SIMD instructions deliver exceptional performance for aggregations and scans. It handles billions of rows per second, supports SQL with analytical extensions, and scales horizontally for petabyte-scale data warehousing and real-time dashboards.

Versatile microservice framework for any protocol

Armeria is an open-source microservice framework from the creator of Netty at LINE Corporation that supports gRPC, Thrift, REST, and GraphQL on a single server and port. It provides built-in decorators for metrics, distributed tracing, load balancing, authentication, rate limiting, circuit breakers, and automatic retries. The framework integrates seamlessly with Spring Boot, Dropwizard, and Reactive Streams while serving automated API documentation with interactive request testing.

Instant database schema diagrams from a single query

ChartDB is an open-source database diagramming tool that converts SQL queries into instant visual entity-relationship diagrams. It supports PostgreSQL, MySQL, SQL Server, MariaDB, SQLite, CockroachDB, and ClickHouse, enabling database engineers to visualize schemas, plan migrations, and generate DDL scripts across different SQL dialects using AI assistance. Available as a free cloud app at chartdb.io or self-hosted via Docker deployment.

Create videos programmatically with React

Remotion is a React framework that enables developers to create videos programmatically using familiar web technologies. Build videos as React components, leveraging CSS, Canvas, SVG, and WebGL for rendering. The framework includes Remotion Studio for browser-based preview with timeline scrubbing and fast refresh. Render locally, on servers, or via AWS Lambda for scalable video production. Ideal for automating social media content, data visualizations, and personalized marketing campaigns.

Open-source Airtable alternative with database power

NocoDB is a free, self-hostable open-source platform that turns any database into a smart spreadsheet interface. It offers grid, gallery, form, Kanban, and calendar views with support for rich field types including links, lookups, rollups, and formulas. NocoDB provides role-based access control, REST APIs, workflow automation, and integrations with services like Slack and Discord — making it a powerful Airtable alternative for teams who want full data ownership.

OAuth 2.1 provider framework for Cloudflare Workers

workers-oauth-provider is Cloudflare's official OAuth provider library for Workers. It implements the provider side of the OAuth 2.1 protocol with PKCE support and RFC 8414 compliance. Handles token management automatically via Cloudflare KV storage. Gives fullstack teams a path to implement OAuth at the edge without heavy auth servers. TypeScript-native with npm package available.

Ultrafast web framework built on Web Standards for every runtime

Hono is a lightweight, ultrafast web framework built on Web Standards that runs on Cloudflare Workers, Deno, Bun, Node.js, AWS Lambda, and any JavaScript runtime. At just 12kB with zero dependencies, it delivers router performance matching raw platform speed. Hono provides first-class TypeScript support with RPC-style client for end-to-end type safety, built-in middleware for auth, CORS, caching, and OpenAPI generation, plus JSX support for server-rendered HTML.

Fine-grained authorization engine by Okta

OpenFGA is an open-source authorization engine inspired by Google Zanzibar, built and maintained by Okta (Auth0). It provides relationship-based access control with a flexible modeling language, sub-millisecond permission checks, and SDKs for major languages. OpenFGA is used by companies including Grafana Labs, Canonical, and Docker for fine-grained access control in multi-tenant applications.

Google Zanzibar-inspired authorization database

SpiceDB is an open-source authorization database inspired by Google's Zanzibar system, providing relationship-based access control (ReBAC) at scale. It defines permissions through a schema language that models relationships between users, resources, and roles, then evaluates authorization checks in single-digit milliseconds. Used by companies like Netflix and GitHub, SpiceDB handles millions of permission checks per second.

Full-text and vector search engine in under 2KB

Orama is a complete search engine and RAG pipeline that runs in browsers, servers, and edge environments in under 2KB. It provides full-text search, vector search, and hybrid search with built-in faceting, filters, geo-search, and typo tolerance. Orama requires no external dependencies and works entirely client-side for instant search experiences, or server-side with Node.js and Deno for larger datasets.

Open-source high-performance key/value datastore

Valkey is a Linux Foundation-backed open-source fork of Redis 7.2.4 under BSD 3-Clause license, created after Redis changed to restrictive licensing. It provides a drop-in Redis replacement for caching, message queues, and real-time data workloads. Valkey 9 adds JSON, Bloom filters, vector search, cluster scaling to 2000 nodes, and over one billion requests per second in benchmarks. Backed by AWS, Google, Oracle, and Ericsson.

YC-backed cloud deployment platform for Rust and Python applications

Shuttle is a YC-backed cloud deployment platform that simplifies deploying Rust and Python backend applications. Developers annotate their code with Shuttle macros to declare infrastructure needs like databases, caches, and secrets, and Shuttle provisions the resources automatically on deployment. Features instant deployment, automatic HTTPS, and infrastructure-from-code. Over 6,100 GitHub stars.

Python library for declarative data loading that LLMs can generate

dlt (data load tool) is a Python library for building data pipelines with declarative, schema-aware loading that is simple enough for LLMs to generate correctly. It extracts data from APIs, databases, and files, normalizes nested structures, handles schema evolution, and loads into warehouses and lakes. Supports 30+ destinations including BigQuery, Snowflake, DuckDB, and PostgreSQL. Over 5,200 GitHub stars.

Multi-LoRA inference server for serving hundreds of fine-tuned models

LoRAX is an inference server that serves hundreds of fine-tuned LoRA models from a single base model deployment. It dynamically loads and unloads LoRA adapters on demand, sharing the base model's GPU memory across all adapters. Built on text-generation-inference with OpenAI-compatible API. Enables multi-tenant model serving without per-model GPU allocation. Over 3,700 GitHub stars.

Postgres sync engine for local-first and real-time applications

ElectricSQL is a sync engine that keeps local application state synchronized with PostgreSQL in real-time. It enables local-first architectures where apps work offline with instant responsiveness, syncing data bidirectionally when connectivity is available. Supports partial replication with shape-based subscriptions to sync only relevant data subsets to each client.